This invention relates to the capture and extermination of fire ants (solenopsis invicta). More particularly, this invention relates to a device that employs suction to collect fire ants and a partial vacuum to asphyxiate the ants.
Since unintentionally introduced into the United States, fire ants have proliferated and spread across a large portion of the southern states. Typically, fire ants live in the ground in mounds which they construct of dirt and other loose materials. These mounds usually extend above the earth's surface and also include tunnels that extend below the earth's surface. Fire ants are particularly dangerous to children and small animals that step onto the mounds and receive multiple fire ant stings. Fire ant stings are generally painful, often become infected, and are particularly dangerous to those that are allergic to the fire ant venom.
A variety of techniques have been employed in an attempt to exterminate fire ants and to cause the fire ants to move to another location. Chemicals have been used for many years to kill fire ants and prevent their reproduction. Recent awareness of the environmental dangers associated with these chemicals, however, have severely limited the use of these chemicals. Therefore, extermination devices have been directed towards the capture and extermination of fire ants without disbursing chemicals into the earth.
A device described in U.S. Pat. No. 4,683,673 to Taylor uses a vacuum to collect the fire ants along with a portion of the mound containing the ants and a hammer mill to crush the ants. However, because fire ants have relatively small and durable bodies that are approximately equal in size to the size of the granules of dirt forming the mounds, the mill described in the Taylor patent was ineffective in exterminating the ants collected. Resultantly, the still living fire ants ejected from the device would simply repopulate the mound.
Another device, described in U.S. Pat. No. 5,214,876 to Sukup, used a vacuum to capture insects and a pesticide to exterminate the captured insects after they were captured. This device when applied to fire ant collection extermination the device was ineffective, however. Because the fire ant collection process requires collecting a portion of the mound, using a pesticide to exterminate the fire ants pollutes the collected portion of the mound.
Still another device, described in U.S. Pat. No. 5,116,219 to Zimmerman, employs a vacuum to capture insects and a fluid to drown the captured insects. U.S. Pat. No. 5,241,779 to Lee describes a device that uses a vacuum to capture insects and electricity to kill the captured insects. Because the capture of fire ants necessarily requires that a portion of the fire ant mound also be collected, however, the use of electricity or fluid for extermination purposes would be ineffective.
Another problem associated with collecting fire ants relates to the behavior of the fire ants themselves. When there are vibrations near the mound or the mound is physically disrupted, the fire ants react defensively. During this defensive reaction process, a number of the fire ants in the mound, including the queen, retreat into the underground tunnels of the mound while the remainder of the fire ants remain in the upper portion of the mound to defend the mound. However, in order to exterminate the mound, the queen must be collected and killed along with a large percentage of the ants in the mound. Therefore, the collection device must be relatively silent as it approaches the mound so as to not elicit defensive behavior from the ants until the collection operation begins. Prior devices have not overcome this hurdle. The device described in U.S. Pat. No. 4,683,673 to Taylor, for example, is mounted on a farm tractor. When the tractor approaches the mound the mound vibrates and the fire ants react defensively well before the device can operate on the mound.